Process for the biological treatment of waste water using microorganisms

ABSTRACT

The present invention relates to the biological treatment of waste water using microorganisms whose living conditions are maintained by addition of oxygen into a contact path. An underwater support frame has a double-walled duct arranged as a contact path such that the duct is placed angularly towards a surface of the water. The duct is made for holding air bubbles to prevent the premature rise of the air bubbles added by an aerator providing air at the beginning of the contact path. The contact path has a suction point at an end which is connected via a fresh organism pipe with the aerator. A connection piece connects the aerator to a suction pipe at the beginning of the contact path. The other end of the suction pipe is connected to a flowing-in opening located at a distance from the aerator contrary to the flow direction, for supplying contaminated water to the aerator before the water actually reaches the contact path.

BACKGROUND OF THE INVENTION

This invention relates to a process for the biological treatment ofwaste water using microorganisms whose living conditions are maintainedby the addition of oxygen into a contact path which is arranged at aslight upward angle towards the water surface and has an interiorair-permeable and an exterior air-impermeable wall, whereby air andcontaminated waste water are added into the contact path for thedevelopment of the microorganisms approximately parallel to the watersurface. The invention also relates to a device for implementing theprocess which has an underwater support frame in which a double-walledduct is arranged with a slight rise towards the water surface and holdsthe air bubbles and which has installations which prevent the prematurerise of the latter and which in its capacity as contact path holds thecontaminated waste water which was added via an aerator and the air.

Such processes are used for the biological decontamination of wastewaters and especially for the regeneration of waters which are seriouslycontaminated and silted because of a lack of oxygen. A known device usedfor this purpose (German Patent 2523591) has a water jet pump which isused to produce a water-air mixture which is then passed for a certaintime period in a pipe in such a way that the air bubbles do not rise toofast. The pipe is extended so far and is equipped with an air-permeableinterior wall and an air-impermeable exterior wall that the individualair bubbles which are as small as possible must travel long distancesand are, during this time, in intensive contact with the water. In thisway oxygen-saturated water is obtained in a certain area so that thebacteria eliminating the sludge are preserved or are able to multiply asquick as possible. The device stands with its support frame on thebottom of the water and may, if needed, be transported from one locationto another. In order to ensure the necessary contact of the air bubbleswith the water, such contact paths have a length of 15 m or more. Insideof the contact paths are installations at which the individualmicroorganisms may also settle and develop in order to ensure theshortest possible and complete purification of the water. But thedisadvantage is that the microorganisms develop more or less randomlydepending on oxygen and food supply, i.e. the added contaminations. Inaddition, the microorganisms which have just achieved optimumeffectiveness are removed with the purified waste water, something whichis partially desired, but which on the other hand constitutes an overallimpediment of the even development of microorganisms. This causesproblems particularly when the composition of the waste water changes.Then, either not enough microorganisms are present, or the presentmicroorganisms cannot change, or the currently required microorganismsare available only in small or minute numbers. British application 587400 publishes a process for waste water treatment in a contact pathwhich is simply aerated cross-wise to flow direction. Part of themicroorganisms leaving the contact path are recycled together withabsorbed sludge into the contact path. Notwithstanding the fact thatthis achieves only an insufficient aeration, i.e. supply of oxygen, thesuggestion of the recycling of sludge obviously shows that only a smallpurification result may be presupposed.

SUMMARY OF THE INVENTION

The invention is based on the task of creating a waste water treatmentprocess with a permanent comparably good purification result which isable to additionally adapt without great expenditure and in a short timeto greatly changing waste water compositions. The invention shall alsodescribe a device required for implementing the invented process.

According to the invention the task is solved in that part of themicroorganisms which have developed in the contaminated water and areleaving the contact path are specifically caught and recycled to thecontact path and that in addition a small partial stream of thecontaminated waste water is given in advance as a kind of indicator intothe settlement area of the microorganisms in the contact path.

In the present process especially those microorganisms which no longerfind a sufficient food supply in the purified water are recycled andthus they are best suited for further elimination of contaminants andalso for further development of the necessary types of microorganism. Inaddition, the microorganisms are able to develop in the contaminatedwater according to its properties so that mostly those types are presentwhich are required for optimized biological waste water treatment whenthe contaminated water reaches the contact path. Such a targeted processimplementation and treatment of the microorganisms is able toadvantageously shorten the process itself since healthy microorganismsbest suited for the respective purification may be made available in asufficient volume.

Also taken into consideration is the fact that the living conditions forthe microorganisms may change significantly depending on the degree ofcontamination and type of contamination of the waste water. The earlyintroduction of small quantities of the waste water from a source beingfed to the contact path which constitutes a kind of early warning systemprevents a sudden destruction of the microorganisms or failure of thepurification. The small partial stream of the waste water remainstotally unaffected, if the waste water may be purified by the existingmicroorganisms. But in the presence of a different contamination ordifferent composition of the waste water this small partial streamalready precultivates the microorganisms suitable for the former so thatthey develop rapidly when the waste water with the changed compositionarrives at the contact path, and ensure that the purification of theoverall waste water continues to be guaranteed also. This advantageouslyenables a smooth transition without requiring special measures. The factis that the adaptation is an entirely automatic result caused by theindicator.

According to a useful version of the invention it is provided that themicroorganisms are recycled into the contact path in the counterstream.The microorganisms which otherwise would no longer find the sufficientfood supply in the purified water and would thus die are now evenlydistributed in the contact path in such a way that they are once againable to feed and propagate optimally. This is caused by theirintroduction into the counterstream which ensures the even distributionof the microorganisms.

Another possibility of even distribution of the microorganisms consistsof taking in the partial stream of the microorganisms at a predetermineddistance in flow direction behind the introduction point of the air andto then distribute it together with the air and water in the contactpath. The microorganisms thus would be introduced either in the area ofthe water jet pump or a little behind it so that they are flushedtogether with the fresh waste water stream in which the large volume ofair bubbles are also introduced into the area of the contact path. Inthe process it is tolerated that the water here is not yet enriched withoxygen so that the method described earlier is actually the better oneaccording to which the microorganisms are introduced into the contactpath in the counterstream at a certain distance to the introductionpoint, i.e. to the aerator.

The number of microorganisms and their formation as such dependsessentially on the oxygen saturation of the water. Because of this aparticularly beneficial removal of the microorganisms should beperformed at a certain distance and the quantity should also be variedaccordingly, whereby it is provided according to the invention that thesuction point is shifted in or contrary to the flow direction dependingon the oxygen saturation of the water and the quantity of presentmicroorganisms.

As a rule it will be sufficient if the partial stream of thecontaminated waste water is introduced at a certain point into thesettlement area of the microorganisms. Then, if a possible quickdistribution becomes necessary or if the change in the water is verydecisive and has been preestablished by way of third measures it may beadvantageous to introduce the partial stream together with air and wastewater into the contact path if the composition of the waste water issuch that it may threaten the microorganisms in their entirety. Thisaccelerates adaptation, in particular if according to anotheradvantageous version of this process the quantity of the partial streamis increased. This prepares a continuous promotion and growth of thosemicroorganisms needed at the arrival of the waste before the waste waterwith the changing composition actually reaches the tank.

Another possibility of adaptation of microorganism development consistsof reducing the addition of contaminated waste water and simultaneouslylocating the suction point closer to the introduction point of air andcontaminated waste water. The changing composition of the waste watermay be taken into consideration in this way, in particular if thealready considered contamination becomes stronger than before, wherebythe invented process ensures that the same purification result isobtained.

In the case of especially grave changes in the composition of the wastewater it may be advantageous to sluice into the cycle via the suctionpoint precultivated microorganisms which are adapted to the new wastewater composition until a stabilization is again obtained. However, thisprocess variation requires continuous observation and control of thewaste water in order to be able to introduce the specifically cultivatedmicroorganisms at the right time, i.e. at a time when they are reallyneeded and when they are then also found again at the suction point andare then recycled again, potentially with further precultivatedmicroorganisms, into the cycle.

For the implementation of the invention we provide a device whichachieves recycling of the cultivated microorganisms into the cycle bylocating a suction point behind the contact path in flow direction, saidsuction point being connected with the aerator via a fresh organismpipe. The microorganisms which are optimized for subsequent cultivationor water purification are thus collected via the suction point and arethen returned through the fresh organism pipe into the aerator or to theaerator. In the process the suction of the aerator may be exploited inorder to use it to catch or take in the microorganisms and to introducethem again into the contact path.

The introduction of the small partial stream of waste water into thearea of the aerator ensures permanent operation. In the process theopenings for streaming in and thus the length of the suction pipe are solong that a sufficient time span is given for precultivating themicroorganisms for the corresponding changing waste water.

A specific recycling of the microorganisms, however, is ensured in thatthe suction point is equipped with a vacuum pump and on the dischargeside with a large number of discharge nozzles which operate incounterstream direction. Such a construction ensures both the taking inof exactly those microorganisms necessary for further cultivation andalso their even application over the entire cross-section of the contactpath, whereby discharge nozzles here have the actual meaning of openingswhich ensure that the microorganisms are mixed in the counterstream atleast for a short distance with the supplied waste water which issaturated with oxygen.

The even taking-in of the water mixed with the microorganisms isoptimized in that the suction point has a large number of suction pipeswhich are distributed over a large diameter.

The locating of the suction point exactly in the area where it catchesmicroorganisms, and particularly healthy microorganisms, is ensuredadvantageously in that the fresh organism pipe is constructed intelescope construction and has a drive. The telescope pipe may be pushedtogether and apart via the drive in order to locate the suction point inthe respectively correct area.

Optimum security against changing waste water is achieved according tothe invention in that the length of the suction pipe is chosen dependingon the average growth speed of anaerobic microorganism present inactivated sludge.

The invention is particularly characterized in that it creates a processand also a device which is able to systematize biological waste watertreatment to such an extent that an even purification result is ensuredeven if the waste water changes in volume of contamination or type ofcontamination. Specific cultivation of especially those microorganismsable to deal with the waste water problems and their early settlement inthe area of the aerator and contact path ensures a continuous permanentoperation of a corresponding device and provides the powerful evenpurification result.

Other details and advantages of the object of the invention result fromthe following description of the corresponding drawing which shows apreferred example with the necessary details and individual parts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a simplified portrayal of a contact path for waste watertreatment,

FIG. 2 shows the portrayal of the distributor pipe for recycling themicroorganisms,

FIG. 3 shows the suction pipe for the indicator water volume, and

FIG. 4 shows an enlarged -portrayal of a device suitable forimplementing the process.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a simplified portrayal of a contact path, whereby thiscontact path (1) is shown here in a simplified manner with only one wall26. However, the structure may also have a double wall, as partiallyindicated at 27. The aerator (2) is located at the beginning of thepath; at the end of the path is located the suction point (4) throughwhich the approximately or entirely developed microorganisms are takenin and are returned in the area of the aerator (2). For this purpose thesuction point has a vacuum pump (5) and is connected via the freshorganism pipe (6) with the aerator (2).

In order to be able to locate the suction point (4) always at thevarious positions, the connections between the individual fresh organismpipe pieces (6) are constructed as telescopic connections (7, 8). Inthis way the pipe (6) may be pushed together or apart respectively,depending on which distance the suction point (4) is supposed to havefrom the aerator (2). A motor drive may be provided here in order to beable to perform the telescoping from the water surface or a floatingplatform.

The end of the fresh organism pipe (6) is formed by a distributor pipe(9) which is shown in detail in FIG. 2. The distributor pipe (9) isequipped here with a large number of discharge nozzles (10, 11) in orderto eject the purified water which contains a multitude of healthymicroorganisms evenly distributed over a correspondingly large diameter,i.e. in the counterstream to the introduced waste water undergoingpurification. The discharge nozzles (10, 11) are principally simpleopenings or bores which are located contrary to the flow direction.

The waste water flowing into the contact path (1) is designated with(12), whereby the increasing degree of purification within the contactpath (1) is indicated by the fact that the distance between the lineswhich run at an angle from the top to the bottom becomes increasinglygreater. (13) designates the oxygen-saturated water which because of itsconsumption by the microorganisms reduces its oxygen content somewhatbehind the aerator (2) through blowing in of air. This is also indicatedin that the density of the dots decreases from the beginning to the endof the path (3). Lines, in this case running from the bottom to theupper left at an angle, are also used to indicate the growth area (14)of the microorganisms. According to the increasing volume ofmicroorganisms the interval between the lines which run from the bottomright to the upper left becomes closer.

The suction pipe (15) is located approximately in the area which isoptimally enriched with microorganisms, said suction pipe having severalopenings in order to be able to remove the microorganism-enriched wateralso from different areas. The individual openings may be equipped withslides so that water with microorganisms may be removed specificallyfrom different horizons.

Also in the area of the aerator (2) a suction pipe (17) is connected viaa connection piece (16). Through this suction pipe dirt water or wastewater which has been taken in well away from the area in front of thecontact path (1) is added in a small quantity into the settlement areaof the microorganisms in order to ensure an early warning in this way.I.e., if the composition of the waste water to be purified changes, areorientation in development will occur simultaneously in the settlementarea of the microorganisms since the corresponding waste water is madeavailable here. According to FIG. 1 a direct introduction of this smallstream of dirt water into the aerator is provided via the connectionpiece (16), but the suction pipe is also able to discharge to the top orbottom edge of the contact path (1).

The suction pipe (17) ends far from the contact path (1) and ends inseveral flowing-in openings (18, 20). Pipe 17 is connected near the endto a pump (19) which enables a small predetermined quantity of the dirtwater to be drawn in through the openings (18, 20) and supplied via pipe17 to the beginning of the contact path having the growth area of themicroorganisms.

FIG. 4 finally shows another simplified construction of a device forimplementing the invented process, whereby here it is also clarifiedthat the contact path (1) in the form of a plexiglass pipe (24) iscoordinated with an underwater support frame (22) through which thedistance of the plexiglass pipe (24) to the water surface is adjustedaccurately for each case and maintained thereof. Dirt water is taken invia the water jet pump (23) and simultaneously air is introduced throughthe nozzles so that a water-air mixture already flows into the area ofthe plexiglass pipe (24) via the aerator (2). In order to prevent theair bubbles from rising and on the other hand to provide surfaces forthe microorganisms to settle on, a large number of installations (25)are provided in the plexiglass pipe (24), whereby many differentconstructions are possible for this purpose. The plexiglass pipe (24),i.e. the contact path (1) runs at a slight angle to the water surface,whereby the second wall is also absent here because the installations(25) provide sufficient safeguards to prevent the premature rising ofthe air bubbles. The construction as a plexiglass pipe (24) additionallyhas the great advantage that the light required for the growth of themicroorganisms is made available in a sufficient volume.

In case of the fresh organism pipe (6) indicated in FIG. 4, the suctionpoint (4) portrayed simply as a connection piece, suctions watercontaining the microorganisms for recycling into the area of the aerator(2). The volume of water to be suctioned can be determined exactly bythe choice of the diameter of the fresh organism pipe (6), the pump andits setting as such.

The installations (25) shown in FIG. 4 are a type of plastic ropes onwhich the microorganisms may settle. But these installations (25, 25',25") may also, as already mentioned, take other forms, whereby it isuseful to use such installations (25, 25', 25") which provide largesurfaces on which the air bubbles and microorganisms may settle.

I claim:
 1. A process for the biological treatment of waste water usingmicroorganisms whose living conditions are maintained by addition ofoxygen into a contact path, the contact path being arranged at a slightupward angle towards a surface of the water and having an interiorair-permeable and an exterior air-impermeable wall, comprising the stepsof:adding air and contaminated waste water into a beginning of thecontact path for developing the microorganisms approximately parallel tothe surface of the water; trapping and suctioning a part of themicroorganisms developed in the contaminated water at a predetermineddistance near an end of the contact path by means of a telescopablefresh organism pipe; recycling the trapped microorganisms to thebeginning of the contact path and additionally introducing a partialstream of the contaminated waste water from a source of the waste waterinto a settlement area of the microorganisms in the beginning of thecontact path to prepare the microorganisms for any change that wouldoccur in the contamination of the waste water being flown to the contactpath.
 2. The process of claim 1, wherein the recycling comprisesrecycling a part of the microorganisms suctioned, to the beginning ofthe contact path against a direction of flow of the waste water.
 3. Theprocess of claim 1, wherein the trapping comprises suctioning part ofthe microorganisms at a predetermined distance in a direction of flownear an end of the contact path, and the recycling comprisesdistributing the trapped microorganisms together with air and the waterin the contact path.
 4. The process of claim 3, wherein further additionof contaminated waste water is decreased when the suction point islocated closer to the beginning of the contact path where the air andthe contaminated waste water are introduced.
 5. The process of claim 1,wherein the suctioning comprises selecting a distance depending on asaturation of the oxygen in the water and on a volume of themicroorganisms present in the contact path for suctioning an optimalpart of the microorganisms and supplying to a source of the contaminatedwaste water.
 6. The process of claim 1, further wherein introducing thepartial stream comprises introducing air and waste water into thebeginning of the contact path for reacting the waste water introducedwith the recycled microorganisms in their entirety.
 7. The process ofclaim 1, wherein the prepared microorganisms are precultivated foradapting to the new waste water composition and are sluiced into thecontact path via a suction point until a stabilization has beenachieved.
 8. An Apparatus for the biological treatment of waste waterusing microorganisms whose living conditions are maintained by additionof oxygen into a contact path, comprising an underwater support frame inwhich a double-walled duct is arranged as a contact path such that theduct is placed angularly towards a surface of the water, and the ducthaving means for holding air bubbles to prevent the premature rise ofthe air bubbles and holds the contaminated waste water added by means ofan aerator providing air at a beginning of the contact path, a suctionpoint at an end of the contact path, the suction point being connectedvia a telescopable fresh organism pipe with the aerator, a connectionpiece for connecting the aerator to a suction pipe at the beginning ofthe contact path, the suction pipe having a diameter at one end smallerthan that of another end, and the other end of the suction pipe beingconnected to a flowing-in opening located at a distance from the aeratorcontrary to the flow direction, for supplying contaminated water to theaerator before the water actually reaches the contact path.
 9. Theapparatus of claim 8, wherein the suction point is connected to pluralinlet pipes arranged to cover a large diameter within the contact path.10. The apparatus of claim 8, wherein the length of the suction pipe isproportional to cover an average growth speed of the microorganismspresent in activated sludge.
 11. An Apparatus for the biologicaltreatment of waste water using microorganisms whose living conditionsare maintained by addition of oxygen into a contact path, comprising anunderwater support frame in which a double-walled duct is arranged as acontact path such that the duct is placed angularly towards a surface ofthe water, and the duct having means for holding air bubbles to preventthe premature rise of the air bubbles and holds the contaminated wastewater added by means of an aerator providing air at a beginning of thecontact path, a suction point at an end of the contact path, the suctionpoint being connected via a fresh organism pipe with the aerator, aconnection piece for connecting the aerator to a suction pipe at thebeginning of the contact path, the suction pipe having a diameter at oneend smaller than that of another end, and the other end of the suctionpipe being connected to a flowing-in opening located at a distance fromthe aerator contrary to the flow direction, for supplying contaminatedwater to the aerator before the water actually reaches the contact path,wherein the suction point is equipped with a vacuum pump near the end ofthe contact path and with plural discharge nozzles for discharging themicroorganisms in a couterstream direction at the beginning of thecontact path.
 12. An Apparatus for the biological treatment of wastewater using microorganisms whose living conditions are maintained byaddition of oxygen into a contact path, comprising an underwater supportframe in which a double-walled duct is arranged as a contact path suchthat the duct is placed angularly towards a surface of the water, andthe duct having means for holding air bubbles to prevent the prematurerise of the air bubbles and holds the contaminated waste water added bymeans of an aerator providing air at a beginning of the contact path, asuction point at an end of the contact path, the suction point beingconnected via a fresh organism pipe with the aerator, a connection piecefor connecting the aerator to a suction pipe at the beginning of thecontact path, the suction pipe having a diameter at one end smaller thanthat of another end, and the other end of the suction pipe beingconnected to a flowing-in opening located at a distance form the aeratorcontrary to the flow direction, for supplying contaminated water to theaerator before the water actually reaches the contact path, wherein thefresh organism pipe is constructed telescopically with a drivecoordinated therewith.